Multifrequency power circuit and probe and NMR spectrometer comprising such a circuit

Abstract

A multifrequency power circuit of an NMR coil, includes two power or transmission line segments called principal line segments, each including a segment of a conductor that is attached to the coil, which attached segments together with the coil constitute a first oscillating circuit that exhibits a determined resonance frequency. The principal line segments consist of controlled-impedance multiconductor line segments, each including at least one other conductor segment that is not attached to coil and that extends into the principal line segment beside corresponding respectively attached conductor segment and that exhibits with the latter a capacitive coupling that is distributed along segments located beside or opposite the conductors. These non-attached conductor segments, together with the coil, attached conductor segments and non-attached conductor segments, and optionally with additional power line segments connected to the non-attached conductor segments, form at least one additional oscillating circuit that has a different resonance frequency.

1. Multifrequency power circuit of a coil, comprising:
 a coil ( 2 ) with two ends, 
 two principal power or transmission line segments ( 3 ,  3 ′), 
 each principal line segment ( 3 ,  3 ′) comprising at least an attached conductor segment ( 4 ,  4 ′) attached to one of the ends of said coil, 
 the attached conductor segments ( 4 ,  4 ′) constituting, with said coil, a first oscillating circuit ( 5 ) that exhibits a determined first resonance frequency, wherein, 
 said principal line segments ( 3 ,  3 ′) further comprise controlled-impedance multiconductor line segments, 
 each multiconductor line segment comprises a non-attached conductor segment ( 6 ,  6 ′) that is not attached to said coil ( 2 ) and that extends into said principal line segment ( 4 ,  4 ′) and that exhibits with the corresponding attached conductor segment ( 4 ,  4 ′), a capacitive coupling that is distributed along conductor segments that are located beside said attached and non-attached conductor segment ( 4 ,  4 ′ and  6 ,  6 ′), 
 said non-attached conductor segments ( 6 ,  6 ′), together with the coil ( 2 ) and the attached conductor segments ( 4 ,  4 ′) and with additional power line segments ( 7 ,  7 ′;  8 ,  8 ′) that are connected to said non-attached conductor segments ( 6 ,  6 ′), form a second oscillating circuit ( 9 ) that has a second resonance frequency that is different from the first resonance frequency of the first oscillating circuit ( 5 ), and 
 each of said first and second oscillating circuits ( 5 ,  9 ) is looped to a respectively adjustable tuning circuit ( 11 ,  11 ′), and is powered by a corresponding respective primary power circuit ( 12 ,  12 ′) via a transfer of energy by one of 
 magnetic coupling with at least one of two attached conductor segments ( 4 ,  4 ′), 
 capacitive coupling with at least one of two non-attached conductor segments ( 6 ,  6 ′), and 
 magneto-capacitive coupling of said primary power circuit ( 12 ,  12 ′) with at least one of the additional line segments ( 7 ,  7 ′;  8 ,  8 ′) that are part of the second oscillating circuit ( 9 ). 
 
   
   
     2. Power circuit according to  claim 1 , wherein each oscillating circuit ( 5 ,  9 ) has a symmetrical structure and composition integrating the attached conductor segments ( 4 ,  4 ′) of identical types and lengths two by two, whereby two attached conductor segments ( 4 ,  4 ′) are part of first oscillating circuit ( 5 ) that has a length that is a multiple of half of the resonance wavelength of said first oscillating circuit ( 5 ). 
   
   
     3. Power circuit according to  claim 1 , wherein the second oscillating circuit has a resonance frequency higher than the resonance frequency of the first oscillating circuit ( 5 ), whereby the length of the segments mutually opposite respectively attached conductor segments ( 4 ,  4 ′) and non-attached conductor segments ( 6 ,  6 ′) of the two principal line segments ( 3 ,  3 ′) provides a degree or level of coupling resulting from the line capacitance distributed along said line segments that ensures a transfer of energy sufficient for the resonance frequency of said second oscillating circuit ( 9 ,  10 ). 
   
   
     4. Power circuit according to  claim 1 , wherein the two principal line segments ( 3  and  3 ′) comprise at least a coating or insulation conductor ( 13 ) forming a shield around the attached and the non-attached conductor segments between the attached and nonattached conductor segments and the outside. 
   
   
     5. Power circuit according to  claim 1 , wherein conductors ( 4 ,  4 ′;  6 ,  6 ′) of the principal line segments ( 3 ,  3 ′) comprise assembled band conductors, with interposed dielectric material, in lines with one of a stratified structure and a sandwich form, and the additional power line segments ( 7 ,  7 ′;  8 ,  8 ′) consist of coaxial lines. 
   
   
     6. Power circuit according to  claim 1 , wherein attached and non-attached conductors segments ( 4 ,  4 ′;  6 ,  6 ′) of the principal line segments ( 3 ,  3 ′) comprise one of concentric and coaxial conductors, with a central wire conductor and one or more concentric tubular conductors that surround the central wire conductor, with interposed dielectric layers, and whereby the additional power line segments ( 7 ,  7 ′;  8 ,  8 ′) comprise coaxial lines. 
   
   
     7. Power circuit according to  claim 1 ,
 further comprising a third oscillating circuit ( 10 ) with a symmetrical structure and with a third resonance frequency that is different from the first and second resonance frequencies, and constituted by an NMR coil ( 2 ), by parts of the attached conductor segments ( 4 ,  4 ′) of the principal line segments ( 3 ,  3 ′) and by additional line segments ( 8 ,  8 ′) that are unique to said third oscillating circuit ( 10 ), 
 wherein the unique additional line segments ( 8 ,  8 ′) are looped to an adjustable tuning circuit ( 11 ″) with a symmetrical structure at one of their ends and connected by their other ends each to one of the attached conductor segments ( 4 ,  4 ′) of the principal line segments ( 3 ,  3 ′) at a non-interfering cold point ( 14  or  14 ′). 
 
   
   
     8. Power circuit according to  claim 1 , further comprising at least one third oscillating circuit ( 10 ) with a symmetrical structure and with a resonance frequency that is different from the first and second resonance frequencies, and wherein the third oscillating circuit ( 10 ) is primarily constituted by additional line segments ( 8 ,  8 ′) that are unique to said other third oscillating circuit ( 10 ), looped to an adjustable tuning circuit or component ( 11 ″) with a symmetrical structure at one of the ends of each of said unique additional line segments ( 8 ,  8 ′) and each connected by their other end to one of the nonattached conductor segments ( 6 ,  6 ′). 
   
   
     9. Power circuit according to  claim 1 , wherein the principal line segments each comprise a coating or shield conductor ( 13 ), with each attached conductor segment ( 4 ,  4 ′) capacitively coupled to a corresponding non-attached conductor segment ( 6 ,  6 ′). 
   
   
     10. Power circuit according to  claim 1 , wherein,
 the principal line segments ( 3 ,  3 ′) comprise one of i) triaxial lines and ii) three concentric conductors ( 4 ,  6 ,  13 ;  4 ′,  6 ′,  13 ′), whereby 
 at least the first oscillating circuit ( 5 ) integrates the attached conductor segments ( 4 ,  4 ′), and 
 said second oscillating circuit ( 9 ) integrates the nonattached concentric conductor segments ( 6 ,  6 ′) of said triaxial lines ( 3 ,  3 ′), 
 whereby a transfer of energy is carried out due to distributed line capacitance of said triaxial lines ( 3 ,  3 ′). 
 
   
   
     11. Power circuit according to  claim 10 ,
 wherein the attaced conductor segments ( 4 ,  4 ′) consist of intermediate conductors of the triaxial lines, and 
 wherein said second oscillating circuit ( 9 ) comprises the non-attached conductor segments ( 6 ,  6 ′), 
 whereby the line capacitance that is distributed between the non-attached conductor segments and intermediate conductors providing a connection by coupling that allows said second oscillating circuit ( 9 ). 
 
   
   
     12. Power circuit according to  claim 11 ,
 wherein the intermediate conductor of the attached conductor segments ( 4 ,  4 ′) each exhibit a cutoff or physical discontinuity ( 15 ,  15 ′) at a respective noninterfering cold point and wherein the additional line segments ( 8 ,  8 ′) of said third additional oscillating circuit ( 10 ) are connected at said cold points, 
 whereby two parts of said intermediate conductor segments ( 4 ,  4 ′) facing each other at said cutoff or discontinuity ( 15 ,  15 ′) are connected together by frequency-selective energy transfer circuits ( 16 ,  16 ′). 
 
   
   
     13. Power circuit according to  claim 10 ,
 wherein said second oscillating circuit ( 9 ) integrates the nonattached conductor segments ( 6 ,  6 ′), 
 whereby the line capacitance that is distributed provides a connection by coupling that allows said second oscillating circuit ( 9 ) to loop to the coil ( 2 ) via the attached conductor segments ( 4 ,  4 ′). 
 
   
   
     14. Power circuit according to  claim 13 ,
 wherein the conductors of the additional line segments( 8 ,  8 ′) of a third oscillating circuit ( 10 ) are connected to the attached conductors segments ( 4 ,  4 ′) at non-interfering cold points ( 14 ,  14 ′), 
 wherein reject filters ( 17 ,  17 ′) insulate the first oscillating circuit ( 5 ) and the third oscillating circuit ( 10 ), and 
 wherein the first and the third oscillating circuits ( 5 ,  10 ) are also insulated from said second oscillating circuit ( 9 ) by reject filters ( 18 ,  18 ′;  19 ,  19 ′). 
 
   
   
     15. Power circuit according to  claim 14 , wherein the reject filters comprise pairs of LC circuits, pairs of filters, and integrating variable capacitors ( 28 ,  28 ′) with a mutual mechanical control for tuning them ( 29 ). 
   
   
     16. Power circuit according to  claim 1 ,
 wherein said primary power circuit ( 12 ,  12 ′) merges with at least one of the oscillating circuits ( 5 ,  9 ) by integrating a part of a common circuit ( 20 ), and 
 wherein said primary power circuit ( 12 ,  12 ′) comprises, a radio-frequency generator ( 21 ) tuned to the determined resonance frequency of associated oscillating circuit ( 5 ,  9 ) and attached to said one oscillating circuit at a terminal of corresponding adjustable symmetrical tuning circuit or component ( 11 ,  11 ′) via a coupling capacitor ( 22 ), and an adaptation circuit or component ( 23 ) that is connected to the other terminal of said adjustable symmetrical tuning circuit or component, 
 whereby the adaptation component ( 23 ) and the adjustable symmetrical tuning component ( 11 ,  11 ′) are part of two circuits ( 12 ,  12 ′, and  5 ,  9 ), comprised of capacitors and the generator ( 21 ) that can operate continuously, intermittently, or in surges. 
 
   
   
     17. Power circuit according to  claim 1 , wherein the primary power circuit ( 12 ,  12 ′) of at least one of the oscillating circuits ( 5 ,  9 ) is comprised of
 a separate circuit, 
 a radio-frequency generator ( 21 ) that is tuned to the determined resonance frequency of the one oscillating circuit, 
 a part coupling with at least one of the two attached conductor segments ( 4 ,  4 ′) connected to the coil ( 2 ) and to the tuning circuit or component ( 11 ,  11 ′), and 
 an adaptation circuit or component ( 23 ) to optimize the coupling and to limit coupling effects in regard to said primary power circuit. 
 
   
   
     18. Power circuit according to  claim 17 ,
 wherein the coupling is a coupling that is essentially magnetic in nature, and 
 wherein the adaptation circuit ( 23 ) is an adjustable capacitor to cancel the inductive reactance at the primary power circuit. 
 
   
   
     19. Power circuit according to  claim 18 ,
 wherein the coupling comprises a primarily magnetic coupling between a first segment ( 24 ,  24 ′) of an associated oscillating circuit ( 5 ,  9 ) and a second segment ( 25 ,  25 ′) opposite of the line that connects the generator ( 21 ) to the adaptation component ( 23 ) in the associated primary power circuit ( 12 ,  12 ′), and 
 whereby the two first and second segments are placed in parallel and close to one another so as to form Lecher lines. 
 
   
   
     20. Power circuit according to  claim 18 , wherein,
 the coupling comprises a symmetrical or asymmetrical magneto-capacitive coupling between a solenoid ( 26 ) that is mounted in series in said primary power circuit ( 12 ,  12 ′), and a capacitor/inductance unit that is mounted in series in the associated oscillating circuit ( 5 ,  9 ), 
 said capacitor is a tuning capacitor corresponding to the tuning component ( 11 ,  11 ′), and inductances ( 27  and  27 ′) of the inductance unit comprise two equivalent inductances that are mounted in series on both sides of said tuning capacitor. 
 
   
   
     21. Power circuit according to  claim 17 , wherein the transfer of energy by coupling between the primary power circuit ( 12 ,  12 ′) and the associated oscillating circuit ( 5 ,  9 ) comprises a double coupling and symmetrically and equivalently assigns corresponding attached and non-attached conductor segments ( 4 ,  4 ′;  6 ,  6 ′) of principal and additional power line segments ( 3 ,  3 ′;  7 ,  7 ′;  8 ,  8 ′). 
   
   
     22. Power circuit according to  claim 1 , wherein at least one of the first oscillating circuit ( 5 ) and the second oscillating circuit ( 9 ,  10 ) integrate one or more band-reject insulation filters ( 17 ,  17 ′;  18 ,  18 ′;  19 ,  19 ′) tuned to the resonance frequency of the other oscillating circuit(s). 
   
   
     23. Insulation circuit according to  claim 22 ,
 wherein the insulation filters are each a pair of filters that are placed symmetrically in the associated oscillating circuit, 
 whereby each filter of a given pair of filters is connected in series with one of the conductor segments that are part of said associated oscillating circuit. 
 
   
   
     24. Power circuit according to  claim 22 ,
 wherein there are three oscillating circuits ( 5 ,  9 ,  10 ), 
 at least one of said three oscillating circuits ( 10 ) integrates two of the insulation filter pairs ( 17 ,  17 ′;  18 ,  18 ′;  19 ,  19 ′), and 
 whereby each insulation filter pair is tuned to the resonance frequency of one of two other oscillating circuits ( 5  and  9 ), one of the insulation filter pairs ( 19 ,  19 ′) being adjustable in frequency. 
 
   
   
     25. Multifrequency power circuit of a coil, comprising:
 a coil ( 2 ) with two ends; 
 two principal power line segments ( 3 ,  3 ′), 
 each principal line segment ( 3 ,  3 ′) comprising 
 i) an attached conductor segment ( 4 ,  4 ′) attached to one of the two ends of said coil, and 
 ii) a controlled-impedance multiconductor line segment, the multiconductor line segment comprising a non-attached conductor segment ( 6 ,  6 ′) that is not attached to said coil ( 2 ) and extending into said principal line segment ( 3 ,  3 ′) beside a corresponding attached conductor segment ( 4 ,  4 ′) and exhibiting, with the corresponding attached conductor segment ( 4 ,  4 ′), a capacitive coupling that is distributed along other conductor segments that are located beside said attached and nonattached conductor segments ( 4 ,  4 ′and  6 ,  6 ′) 
 a first oscillating circuit comprised of one of the attached conductor segments ( 4 ,  4 ′) and said coil, the first oscillating circuit having a determined first resonance frequency; and 
 a second oscillating circuit ( 9 ,  10 ) comprised of one of the nonattached conductor segments ( 6 ,  6 ′), said coil ( 2 ), a corresponding one of the attached conductor segments ( 4 ,  4 ′), and additional power line segments ( 7 ,  7 ′;  8 ,  8 ′) that are connected to said nonattached conductor segment ( 6 ,  6 ′), the second oscillating circuit ( 9 ,  10 ) having a second resonance frequency that is different from the first resonance frequency, wherein, 
 each of said first and second oscillating circuits ( 5 ,  9 ,  10 ) is looped to a respectively adjustable tuning circuit ( 11 ,  11 ′,  11 ″), and is powered by a corresponding respective primary power circuit ( 12 ,  12 ′,  12 ″) via a transfer of energy by one of 
 i) magnetic coupling with at least one attached conductor segment ( 4 ,  4 ′), 
 ii) capacitive coupling with at least one non-attached conductor segment ( 6 ,  6 ′), and 
 iii) magneto-capacitive coupling of said primary power circuit ( 12 ,  12 ′,  12 ″) with at least one additional line segment ( 7 ,  7 ′;  8 ,  8 ′) that is part of the second oscillating circuit ( 9 ,  10 ). 
 
   
   
     26. Multifrequency power circuit of a coil, comprising:
 a coil ( 2 ) with two ends; 
 two principal power line segments ( 3 ,  3 ′), 
 each principal line segment ( 3 ,  3 ′) comprising 
 i) an attached conductor segment ( 4 ,  4 ′) attached to one of the two ends of said coil, and 
 ii) a controlled-impedance multiconductor line segment, the multiconductor line segment comprising a non-attached conductor segment ( 6 ,  6 ′) that is not attached to said coil ( 2 ) and extending into said principal line segment ( 3 ,  3 ′) beside a corresponding attached conductor segment ( 4 ,  4 ′) and exhibiting, with the corresponding attached conductor segment ( 4 ,  4 ′), a capacitive coupling; 
 a first oscillating circuit comprised of one of the attached conductor segments ( 4 ,  4 ′) and said coil, the first oscillating circuit having a determined first resonance frequency; and 
 a second oscillating circuit ( 9 ,  10 ) comprised of one of the nonattached conductor segments ( 6 ,  6 ′), said coil ( 2 ), and a corresponding one of the attached conductor segments ( 4 ,  4 ′), the second oscillating circuit ( 9 ,  10 ) having a second resonance frequency that is different from the first resonance frequency, wherein, 
 each of said first and second oscillating circuits ( 5 ,  9 ,  10 ) is looped to a respectively adjustable tuning circuit ( 11 ,  11 ′,  11 ″), and is powered by a corresponding respective primary power circuit ( 12 ,  12 ′,  12 ″) via a transfer of energy by one of 
 i) magnetic coupling with at least one attached conductor segment ( 4 ,  4 ′), and 
 ii) capacitive coupling with at least one non-attached conductor segment ( 6 ,  6 ′).